/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
using PdfSharp.Internal;
using PdfSharp.Pdf.IO;

namespace PdfSharp.Pdf
{
  /// <summary>
  /// Represents a PDF object identifier, a pair of object and generation number.
  /// </summary>
  [DebuggerDisplay("({ObjectNumber}, {GenerationNumber})")]
  public struct PdfObjectID : IComparable
  {
    /// <summary>
    /// Initializes a new instance of the <see cref="PdfObjectID"/> class.
    /// </summary>
    /// <param name="objectNumber">The object number.</param>
    public PdfObjectID(int objectNumber)
    {
      Debug.Assert(objectNumber >= 1, "Object number out of range.");
      this.objectNumber = objectNumber;
      this.generationNumber = 0;
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="PdfObjectID"/> class.
    /// </summary>
    /// <param name="objectNumber">The object number.</param>
    /// <param name="generationNumber">The generation number.</param>
    public PdfObjectID(int objectNumber, int generationNumber)
    {
      Debug.Assert(objectNumber >= 1, "Object number out of range.");
      //Debug.Assert(generationNumber >= 0 && generationNumber <= 65535, "Generation number out of range.");
#if DEBUG
      // iText creates generation numbers with a value of 65536... 
      if (generationNumber > 65535)
        Debug.WriteLine(String.Format("Generation number: {0}", generationNumber));
#endif
      this.objectNumber = objectNumber;
      this.generationNumber = (ushort)generationNumber;
    }

    /// <summary>
    /// Gets or sets the object number.
    /// </summary>
    public int ObjectNumber
    {
      get { return this.objectNumber; }
      set { this.objectNumber = value; }
    }
    int objectNumber;

    /// <summary>
    /// Gets or sets the generation number.
    /// </summary>
    public int GenerationNumber
    {
      get { return this.generationNumber; }
      set { this.generationNumber = (ushort)value; }
    }
    ushort generationNumber;

    /// <summary>
    /// Indicates whether this object is an empty object identifier.
    /// </summary>
    public bool IsEmpty
    {
      get { return this.objectNumber == 0; }
    }

    /// <summary>
    /// Indicates whether this instance and a specified object are equal.
    /// </summary>
    public override bool Equals(object obj)
    {
      if (obj is PdfObjectID)
      {
        PdfObjectID id = (PdfObjectID)obj;
        if (this.objectNumber == id.objectNumber)
          return this.generationNumber == id.generationNumber;
      }
      return false;
    }

    /// <summary>
    /// Returns the hash code for this instance.
    /// </summary>
    public override int GetHashCode()
    {
      return this.objectNumber ^ this.generationNumber;
    }

    /// <summary>
    /// Determines whether the tow objects are equal.
    /// </summary>
    public static bool operator ==(PdfObjectID left, PdfObjectID right)
    {
      return left.Equals(right);
    }

    /// <summary>
    /// Determines whether the tow objects not are equal.
    /// </summary>
    public static bool operator !=(PdfObjectID left, PdfObjectID right)
    {
      return !left.Equals(right);
    }

    /// <summary>
    /// Returns the object and generation numbers as a string.
    /// </summary>
    public override string ToString()
    {
      return this.objectNumber.ToString() + " " + this.generationNumber.ToString();
    }

    /// <summary>
    /// Creates an empty object identifier.
    /// </summary>
    public static PdfObjectID Empty
    {
      get { return new PdfObjectID(); }
    }

    /// <summary>
    /// Compares the current object id with another object.
    /// </summary>
    public int CompareTo(object obj)
    {
      if (obj is PdfObjectID)
      {
        PdfObjectID id = (PdfObjectID)obj;
        if (this.objectNumber == id.objectNumber)
          return this.generationNumber - id.generationNumber;
        return this.objectNumber - id.objectNumber;
      }
      return 1;
    }
  }
}
